1. Field of the Invention
This invention relates to a drain valve. In particular, the invention relates to a drain valve for aircraft fuel tanks that is simpler to operate, and, therefore, less prone to breakage.
2. Description of Related Art
Aircraft fuel tanks generally require drain valves located at the low points of the fuel tanks in order to remove water caused by condensation. These drain valves are also used to sample the fuel for contamination. Existing drain valves require the operator to perform a sequential, push-and-turn operation to open the valve. A different, sequential, push-and-turn operation is required to close the valve. If the operator wishes to change the valve seal by operating the valve to the “service” position, another, different, sequential, push-and-turn motion is required. Since valves that are made by different manufacturers are operated by means of different, sequential, push-and-turn operations, the operator must try to ascertain how a given valve is operated. If the information is not available, the operator is forced to experiment with various motions, and consequently, drain valve breakage occurs in some cases. An example of such a drain valve is disclosed in U.S. Pat. No. 4,880,029, which is incorporated by reference herein.
Accordingly, a twist cam valve that addresses the drawbacks of the prior art would be highly desirable.